Highly purified preparations of the heme-controlled rabbit reticulocyte repressor (HCR) contain a 3':5'-cyclic AMP independent protein kinase activity which phosphorylates the low molecular weight (approximately 38,000) polypeptide chain of EIF-2. HCR inhibition of peptide initiation appears to involve this reaction. Two translational inhibitors have been isolated from different lines of unstimulated Friend cells. Both inhibitors block peptide initiation on reticulocyte ribosomes with natural mRNA. One blocks peptide initiation at the EIF-2 reaction and phosphorylates a subunit of this factor. This inhibitor appears to be similar to HCR in its physical properties and function except that no effect of heme on its formation has been detected. The other Friend cell inhibitor is different than HCR. Preparations of this inhibitor do not contain detectable protein kinase activity but prevent binding of mRNA to the 40S ribosomal initiation complex. Aminoacyl-tRNA synthetase from eukaryotic cells are distributed into three different fractions based on their rate of sedimentation; free as single enzymes, in at least one complex of about 18S containing other synthetases, and bound to ribosomes. The distribution pattern of synthetases into these fractions is different in different eukaryotic cells and tissues. BIBLIOGRAPHIC REFERENCES: Inhibition of Friend Murine Leukemia Virus Production by Low Ionic Strength Medium. M. Ussery, R. Ramirez-Mitchell, and B. Hardesty. J. of Virology 17: 453-461 (1976). Comparison of Free and Ribosome Bound Phenylalanyl-tRNA Synthetase from Rabbit Reticulocyte. W. Tanaka, K. Som, and B. Hardesty. Arch. Biochem. Biophys. 172: 252 (1976).